Deletion of Edn signaling genes affects vertebrate-like features in lampreys

Edn signaling genes were likely directing their targets, Neural Crest Cells, right from the start of vertebrate evolution, new research reveals.

Researchers led by a team from the University of Colorado, Boulder used CRISPR technology to delete genes in the lamprey. The lamprey is assumed to be a sort-of intermediary for invertebrate to vertebrate evolution that shared a common ancestor with vertebrates 500 million years ago.

By observing that the deletions affected vertebrate-like features in the lamprey, the researchers inferred that the Edn signaling genes preexisted this branch point of the evolutionary tree.

"Lampreys are jawless fishes that last shared a common ancestor with modern jawed vertebrates around 500 million years ago," the authors wrote. "Thus, comparisons between lampreys and gnathostomes can identify deeply conserved and evolutionarily flexible features of vertebrate development."

The research, published in Nature, finds that the control genes that are critical to forming the skeleton of the head and other unique vertebrate features existed before the lamprey.

"Every animal essentially has the same basic core set of LEGO pieces to make them. What this paper shows is that vertebrates have a few special pieces in addition to that, and we identify those special pieces,"  Daniel Medeiros, senior author of the paper and associate professor of ecology and evolutionary biology, told phys.org.

Kelsey Simpkins of the University of Colorado, Boulder explained that the genes they deleted are known as the "Endothelin signaling pathway, a set of genes that influence how cells talk to each other."

"The researchers found this gene family is responsible for allowing neural crest cells – cells that develop into unique vertebrate traits like skeletal parts, pigment cells and our peripheral nervous system – to proliferate and specialize into different roles throughout the body."

Neural crest cells (NCCs) are essential for vertebrate development, including bone, muscle and specialized nerve cells. The NCC's are unique to vertebrates and directed by endothelin receptors and ligands (Edn signaling).

"Rather than looking at fossils, we use tools like molecular biology and genetics to try to understand how evolution has happened, kind of like genetic paleontology," Medeiros told phys.org. "In the deepest molecular genetic terms, we're trying to reverse engineer how a creature evolves. It's the closest you can get to Jurassic Park."